Effective mass
11 g
| Bearing | Gimbal |
|---|---|
| Pivot to spindle | 311 mm The mounting distance — where the arm sits relative to the platter. |
| Overhang | 12.5 mm |
| Effective length | 323.5 mm Pivot to stylus: the mounting distance plus the overhang. |
| Offset angle | 16.75° As published. The arm's geometry follows Baerwald (Löfgren A) · IEC. |
| Mounting | Ortofon 3-screw, 40 mm PCD |
| Source | ortofon.com Checked against the source. |
Other configurations
with LH-9000 headshell — 27.8 g
A different headshell or counterweight changes the effective mass by more than a resonance calculation can absorb, so each configuration is listed separately.
Effective mass is not what the arm weighs. It is the mass the cartridge has to accelerate at the stylus tip, and with the cartridge's compliance it sets where the pairing resonates — ideally between 8 and 12 Hz. Add 0.5 g for mounting hardware when you work it out.
Ortofon and AS-309R are the trademarks of their owner. Bool Audio is independent of them, and this page is not endorsed by them.
Who makes these
Bool Audio is a father and son making hi-fi components in a small UK workshop. We build the Clear Wave unipivot tonearm and the Clear Wave 2.0 tonearm cable, both for the Linn LP12. These calculators began as our own bench arithmetic. They are free to use, there is nothing to install, and they take no view on which cartridge you should own.